Comparison of Triple Interaction of Tillage, Nitrogen Fertilizer, and Barley Varieties on Biochemical Traits and Chlorophyll Content

This study investigates the effects of different tillage methods and urea fertilizer with nitrapyrin for increasing nitrogen efficiency on quantitative and qualitative traits of barley varieties in a factorial split randomized complete block design with three replications during two crop years 2016-2017 at the Research Field of Nuclear Science and Technology Research Institute, Iran Atomic Energy Organization (Zafaranieh Farm in Karaj). Experimental treatments included tillage system at two levels (conventional tillage and minimum tillage only by disk), nitrogen fertilizer at three levels (no fertilizer or control, urea fertilizer (150 kg/ha), urea fertilizer (150 kg/ha) with nitrapyrin, and two barley varieties (Walfajer cultivar and mutant Roodasht). Tillage factor was placed in a main plot and urea fertilizer and barley varieties were factorialized in sub-plots. Results showed that tillage factor had significant effects on grain fiber and starch contents, grain protein, grain protein yield, chlorophyll content, and leaf phosphate. Grain fiber content, grain protein yield, nitrate reductase (NR), and grain nitrogen were affected significantly by triple interaction of tillage, nitrogen, and variety. Grain physiological, morphological, and chemical components decreased under conventional tillage conditions, while an increase occurred in the plant height only. Improved soil fertility with increased moisture and organic matter content at minimum tillage led to enhancements in plant physiological and morphological traits. The application of nitrification inhibitor with urea fertilizer increased NR efficiency and nitrogen uptake efficiency in the plant. However, NR, plant and grain nitrogen contents, efficiency, and harvest index were lowermost in the absence of nitrification inhibitor (nitrapyrin).